Process of forming an encapsulated magnet assembly

Abstract

A process of forming an encapsulated magnet assembly is provided, the process comprising welding a second portion of a housing cover formed of a non-magnetic material to a first portion of a housing cover formed of a magnetic material to provide a welded housing cover and subsequently heat-treating the welded housing cover at a temperature effective to relieve weld stress; disposing a magnet within a housing comprising at least one wall formed of the non-magnetic material and defining at least one aperture; and welding the heat treated welded housing cover to the housing such that the second portion of the housing cover is fixedly attached to the housing wall to hermetically seal the aperture. In one embodiment, the magnet of the encapsulated magnet assembly is a permanent magnet, and in an alternate embodiment an electromagnet. In one embodiment the encapsulated magnet assembly is a component of a stator-rotor assembly.

The invention claimed is: 
     
       1. A process of forming an encapsulated magnet assembly, the process comprising:
 welding a second portion of a housing cover formed of a non-magnetic material to a first portion of a housing cover formed of a magnetic material to provide a welded housing cover and subsequently heat-treating the welded housing cover at a temperature effective to relieve weld stress, wherein heat-treating the welded housing cover comprises exposing the welded housing cover to a double age hardening process; 
 disposing a magnet within a housing comprising at least one wall formed of the non-magnetic material and defining at least one aperture; and 
 welding the heat treated welded housing cover to the housing such that the second portion of the housing cover is fixedly attached to the housing wall to hermetically seal the aperture. 
 
     
     
       2. The process according to  claim 1 , wherein the magnet is a permanent magnet. 
     
     
       3. The process according to  claim 1 , wherein the magnet is an electromagnet. 
     
     
       4. The process according to  claim 1 , wherein said disposing a magnet within the housing comprises attaching electromagnetic components of an electromagnet to the first portion of the heat treated welded housing cover. 
     
     
       5. The process of  claim 1 , wherein the magnetic material comprises a precipitation hardened martensitic stainless steel comprising 10 to 20 wt % chromium based on a total weight of the precipitation hardened martensitic stainless steel. 
     
     
       6. The process of  claim 1 , wherein the non-magnetic material comprises a nickel based alloy comprising 40 to 70 wt % nickel based on a total weight of the nickel based alloy. 
     
     
       7. The process of  claim 1 , wherein welding a second portion of a housing cover formed of a non-magnetic material to a first portion of a housing cover formed of a magnetic material to provide a welded housing cover comprises an autogenous electron beam process, a laser weld process, a TIG weld process, a MIG weld process, an arc weld process, a torch weld process or combinations comprising at least one of the foregoing processes. 
     
     
       8. The process of  claim 1 , wherein welding a second portion of a housing cover formed of a non-magnetic material to a first portion of a housing cover formed of a magnetic material to provide a welded housing cover comprises a laser weld process. 
     
     
       9. The process of  claim 1 , wherein heat-treating the welded housing cover comprises solution annealing at an elevated temperature and subsequently cooling to below 32° C.; followed by at least one precipitation-hardening cycle. 
     
     
       10. The process according to  claim 1 , wherein the encapsulated magnet assembly is a stator configured to drive a magnetically susceptible rotor.